1. Field of the Invention
The invention is a process for producing devices with evaporated gold films.
2. Description of the Prior Art
Gold films are extensively used in a variety of applications including for decorative articles, e.g., watches, rings, earrings, cuff links, etc.), optical mirrors and other optical devices, as well as electronic circuitry. Gold evaporation is often a very convenient way of producing such gold films. Although such films can often be made with perfectly satisfactory properties for some applications, usually the gold atoms are deposited electrolytically or are driven into the surface by such procedures as sputtering or ion bombardment so as to produce adherent gold layers which are not easily removed by scraping. The processing parameters are most critical when gold is evaporated on non-metallic surfaces such as glass, plastics, ceramics native oxide coatings on various semiconductors such as silicon dioxide coatings on silicon wafers. Many attempts have been made to improve the adherence of evaporated gold, simplify processing and obtain greater reliability in putting down gold layers especially on non-metallic surfaces. Typical examples are the use of chromium undercoats or titanium-palladium undercoatings. These procedures are often tedious and require elaborate equipment and usually require particularly stringent processing conditions (e.g., temperature, surface preparation, etc.). For some applications, such undercoating material might readily oxidize or be subject to chemical electrolytic action including cation diffusion. Also, for many applications, insulting contacts are required as for electrode connections on crystals, capacitors, etc.